[PATCH] i386/x86-64: Don't ack the APIC for bad interrupts when the APIC is not enabled

It's bad juju to touch the APIC when it hasn't been enabled.
I also moved ack_bad_irq for x86-64 out of line following i386.

Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 24 insertions, 1 deletions

diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index acd3f1e34ca6..98a5c23cf3df 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -75,8 +75,10 @@ void ack_bad_irq(unsigned int irq)
          * holds up an irq slot - in excessive cases (when multiple
          * unexpected vectors occur) that might lock up the APIC
          * completely.
+         * But only ack when the APIC is enabled -AK
          */
-        ack_APIC_irq();
+        if (!cpu_has_apic)
+                ack_APIC_irq();
 }
 
 void __init apic_intr_init(void)
@@ -1303,6 +1305,7 @@ int __init APIC_init_uniprocessor (void)
         if (!cpu_has_apic && APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
                 printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
                         boot_cpu_physical_apicid);
+                clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
                 return -1;
         }
 
diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index c02218b3ae2b..6147770b4347 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -72,6 +72,26 @@ int get_maxlvt(void)
         return maxlvt;
 }
 
+/*
+ * 'what should we do if we get a hw irq event on an illegal vector'.
+ * each architecture has to answer this themselves.
+ */
+void ack_bad_irq(unsigned int irq)
+{
+        printk("unexpected IRQ trap at vector %02x\n", irq);
+        /*
+         * Currently unexpected vectors happen only on SMP and APIC.
+         * We _must_ ack these because every local APIC has only N
+         * irq slots per priority level, and a 'hanging, unacked' IRQ
+         * holds up an irq slot - in excessive cases (when multiple
+         * unexpected vectors occur) that might lock up the APIC
+         * completely.
+         * But don't ack when the APIC is disabled. -AK
+         */
+        if (!disable_apic)
+                ack_APIC_irq();
+}
+
 void clear_local_APIC(void)
 {
         int maxlvt;